1. Field of the Invention
The present invention relates to an illumination display switching device, and more particularly, to an illumination display switching device that improves visibility by illuminating from a backside a display design such as letter, symbol, or figure, which is formed on a switch knob for operating a push button-type switch.
2. Description of the Related Art
As an example of the illumination display switching device, JP-A-2008-192407 suggests an illumination display switching device that is used for an operation switch of an air conditioner device, an audio device and the like of a vehicle. According to this device, a switch knob that is supported to be slidable in an operation direction of the switch and a push bar that protrudes from a backside of the switch knob are integrally molded with a transparent resin material, a leading end of the push bar is mounted with being contacted to an operation part of a push button-type switch and the switch knob is pushed to operate the push button-type switch. Also, in order to form a display design for identifying a type and the like of the switch such as letter, symbol, figure and the like on a display operation surface of the switch knob, the switch knob is molded with a light-transmitting resin and a part except for the display design is colored with a light-blocking paint so that the light is emitted through the display design only.
In particular, according to JP-A-2008-192407, the push button-type switch has a hollow cylindrical shape, a light emitting diode (LED) is accommodated in the cylinder to thus form a switch part on a cylindrical wall and an axis of the push bar operating the push button-type switch and molded with the transparent resin is matched with a center of the LED. According to this configuration, since a center of the operation of the switch knob and a central axis of the push button-type switch can be matched, a feeling (operation feeling) of the switch knob can be improved. Also, although a diameter of a part of the push bar, which is light-coupled to the LED, is small, a part that is connected to a display part of the switch knob is formed to have a cone-shaped enlarged part and an outer surface of the push bar is painted so as to suppress the internal light from leaking to the outside, thereby improving illumination performance of the display design.
As another example of the illumination display switching device, JP-A-2000-173379 discloses that a cylindrical switch knob, which is supported to a cylindrical attachment member to be slidable in an operation direction of a switch, is arranged above a push button-type switch and a light source. The switch knob has a disc-shaped upper part having a display design that is formed at an upper end of a hollow cylinder of the switch knob and is made of at least a light-transmitting material. A part except for the display design of the switch knob is covered by a light-blocking member, so that only the display design is illuminated to thereby improve the visibility. Meanwhile, the hollow cylinder of the switch knob is provided with a cylindrical light guide member inserted therein, which guides the light of the light source arranged just below the switch knob towards a display part, or is configured as an empty space. Also, a lower end of the hollow cylinder of the switch knob is formed at a part thereof with a protruding push part that operates the push button-type switch. Also, a spring that pushes up and maintains the switch knob is provided to abut on the lower end of the hollow cylinder.